Spearfishing Freediving Physiology for Spearfishing 2 — Questions and Answers
Question 1: What is 'static apnea' and how does it help spearfishers improve performance?
- Breath-hold while swimming horizontally on the surface
- Breath-hold without movement to train CO2 tolerance and extend maximum breathhold duration (Correct answer)
- A relaxation technique used on the boat
- Vertical descent training
Correct answer: Breath-hold without movement to train CO2 tolerance and extend maximum breathhold duration
Static apnea trains the diver's tolerance to CO2 buildup and psychological discomfort, directly translating to longer, more relaxed breathhold times underwater.
Question 2: What physical phenomenon causes a diver's wetsuit to provide less buoyancy at depth compared to the surface?
- Salt concentration changes
- Neoprene cells compress under pressure, reducing the air trapped in the material and decreasing buoyancy (Correct answer)
- Water temperature increases at depth
- The wetsuit absorbs water progressively
Correct answer: Neoprene cells compress under pressure, reducing the air trapped in the material and decreasing buoyancy
Neoprene is composed of closed-cell foam; as pressure increases with depth, the cells compress, reducing suit thickness and buoyant lift, causing the diver to become more negatively buoyant.
Question 3: What is the role of the spleen in elite freedivers' breath-hold performance?
- It filters toxins during dives
- The spleen contracts under diving stimulus, releasing stored red blood cells and increasing blood oxygen-carrying capacity (Correct answer)
- It regulates buoyancy
- It controls heart rate during the dive reflex
Correct answer: The spleen contracts under diving stimulus, releasing stored red blood cells and increasing blood oxygen-carrying capacity
The spleen acts as a blood oxygen reservoir; during breath-hold, it contracts and injects RBC-rich blood into circulation, boosting oxygen capacity — a key adaptation in trained freedivers.
Question 4: What physical symptom should a spearfisher take as a warning sign to immediately surface during a dive?
- Feeling cold
- Diaphragm contractions becoming very strong and rhythmic (strong urge to breathe contractions) (Correct answer)
- Mild ear pressure
- Seeing a large fish
Correct answer: Diaphragm contractions becoming very strong and rhythmic (strong urge to breathe contractions)
Strong, involuntary diaphragmatic contractions indicate dangerously low oxygen; these are the body's emergency signals to breathe and must be respected immediately.
Question 5: Why should spearfishers avoid consuming large meals before diving?
- Food makes the wetsuit too tight
- Digestion increases metabolic oxygen demand, reducing available oxygen for the dive and increasing blackout risk (Correct answer)
- Food causes vertigo underwater
- Regulations prohibit diving after eating
Correct answer: Digestion increases metabolic oxygen demand, reducing available oxygen for the dive and increasing blackout risk
Active digestion diverts blood oxygen to the digestive system and raises metabolic rate, reducing the oxygen available for the dive and increasing susceptibility to shallow water blackout.
Question 6: What effect does cold water have on a spearfisher's breathhold capacity?
- Cold water increases breathhold time indefinitely
- Cold water triggers a stronger mammalian dive reflex but also increases metabolic oxygen consumption, generally reducing safe bottom time (Correct answer)
- Cold water has no effect on breathhold
- Cold water only affects equalization
Correct answer: Cold water triggers a stronger mammalian dive reflex but also increases metabolic oxygen consumption, generally reducing safe bottom time
While cold water enhances the dive reflex, the body burns more oxygen maintaining core temperature in cold water, resulting in shorter safe dive times compared to warm conditions.
Spearfishing Freediving Physiology for Spearfishing 2
What is 'static apnea' and how does it help spearfishers improve performance?